Revise GCSE Physics

Question:What is the visible spectrum?

The visible spectrum is the seven colours of visible light. The seven colours of the visible spectrum are also called the colours of the rainbow. Visible spectrum pic

White light is a mixture of these seven different colours. If we shine a beam of white line through a prism, the colours are separated as shown below.

The process of separating colour of light using a prism is called dispersion.

The simplest way to think about the word spectrum is to think that it means 'range' so the visible spectrum is just the range of colours that make up light.

Dispersion of white light by prism: diagream Dispersion of white light by prism: diagream These diagrams show the dispersion of white light into the seven colours of the visible spectrum.

A simple way to remember the visible spectrum is the mnemonic:


Where the letters represent the first letter of each of the seven colours:

Red Orange Yellow Green Blue Indigo Violet.

In dispersion the different colours are bent by different amounts as they pass through the prism. This is confirmation that there must be something different about each of the seven colours (Although the fact that our eyes react differently to each of the colours should be sufficient).